This invention relates to machines for packaging cigarettes or the like articles, and particularly to the device which, in these machines, is designed to form orderly groups of cigarettes, said groups consisting of "n" superimposed layers of cigarettes and being formed each in a collecting container which is passed intermittently through a series of "n" feeding stations wherein each container receives a layer of cigarettes during its dwell period, each station comprising a plurality of mutually adjacent and substantially vertical cigarette-feeding channels in which the cigarettes descend horizontally superimposed to each other and in single columns to form, below the bottom outlets of the feeding channels, a layer of cigarettes which is expelled in the axial direction of the cigarettes to be transferred into an opposite collecting container.
Generally, the individual layers of cigarettes are introduced into the collecting container at different levels in the successive feeding stations. Moreover, the individual layers of cigarettes are introduced, preferably simultaneously, into a group of "n" successive collecting containers present at the "n" feeding stations. The spacing between the successive containers may be the same as the spacing between the feeding stations, or it may be a sub-multiple and particularly one half of said spacing. The collecting containers may be supported either by an endless conveyor, e.g. a belt conveyor or a chain conveyor, or (in angularly equally-spaced positions) by a rotatable drum.
A disadvantage of the cigarette-packaging machines utilizing devices of the type specified above is that, upon starting the machine, before reaching a steady running condition, incomplete groups of cigarettes are formed and must be discarded by expelling them from the respective collecting containers, for example, by means of jets of compressed air. In fact, for example, in case of a packaging machine with three feeding stations for the formation of respective layers of 7, 6 and 7 cigarettes and with a spacing between the collecting containers which is equal to one half of the spacing between the stations, upon staring the machine and before obtaining a continuous succession of containers with complete groups of cigarettes, two collecting containers with only the bottom layer of 7 cigarettes and two successive collecting containers with only the bottom layer of 7 cigarettes and intermediate layer of 6 cigarettes will be obtained.
The heretofore known packaging machines comprising devices of the type described above and utilizing a hot quick-drying glue have the additional disadvantages to require a number of complete groups of cigarettes to be discarded before the machine reaches a pre-established minimum speed. In fact, at any speed lower than that, the wrapping sheets provided with glue and intended to enwrap the orderly groups of cigarettes cannot be fed because the glue would have dried when they reach the corresponding groups of cigarettes.
Another disadvantage of the known devices forming orderly groups of cigarettes in the packaging machines resides in the fact that when the work-shift of a packaging machine is over, or in case of a programmed inactivation thereof, incomplete groups of cigarettes are left in the collecting containers between the extreme feeding stations, and they must be removed. Complete groups of cigarettes to be removed are also left within collecting containers downstream of the feeding stations if a hot quick-drying glue is used.
These disadvantages are overcome by the present invention which, at each feeding station, provides an interceptor which is movable between an active position wherein it prevents the cigarettes from exiting out of the bottom outlets of the respective feeding channels, and a rest position wherein it permits the cigarettes to exit from the outlets of the feeding channels, means being provided to control the interceptors of the successive feeding stations sequentially in the direction of advance of the collecting containers, beginning from the first feeding station, whereby upon starting the packaging machine, after moving the interceptor of the first feeding station from its active position to its rest position and transferring the first cigarette layer into a first collecting container, to be filled completely, the interceptor(s) of the successive feeding station(s) will be moved sequentially from the active position to the rest position thereof only when said container reaches or is about to reach the respective feeding station to receive the corresponding cigarette layer, whereas when a work-shift is over or in case of a programmed inactivation of the packaging machine, the interceptors of the individual feeding stations are moved sequentially from their rest position to their active position, each after or simultaneously with the transfer of the respective layer of cigarettes into a last collecting container to be filled completely.
If a hot quick-drying glue is used, the cycle of movements of the interceptors from their active position to their rest position is started only when the packaging machine reaches the minimum permitted production speed.
It is apparent from the above that, by virtue of the device according to the invention, in case of a programmed inactivation of a packaging machine or at the end of its work-shift, a condition will be obtained wherein a succession of collecting containers are all provided with complete groups of cigarettes and no trailing collecting container will be left with incomplete groups of cigarettes. Since, in case of inactivation of the packaging machine, all the complete groups of cigarettes will be packaged, all the collecting containers will be left completely empty, thus facilitating the normal maintenance operations. Even upon staring the packaging machine (which occurs with completely empty collecting containers) the formation of incomplete groups of cigarettes, to be discarded and expelled from the collecting containers, is avoided because the outflow of the cigarette layers from the bottom outlets of the feeding channels in the feeding stations following the first station is permitted only when a collecting container already supplied with a cigarette layer in the first feeding station reaches the successive feeding station(s) to receive the respective cigarette layer(s). If a hot quick-drying glue is used, upon starting the packaging machine, the formation of complete groups of cigarettes to be discarded before the packaging machine reaches the minimum speed required for a correct operation is avoided, because the outflow of cigarette layers from the bottom outlets of the feeding channels at the feeding stations is permitted only when the packaging machine has reached the required minimum speed.
The invention may be carried out in various ways. Specifically, either the interceptors associated with the feeding channels in the individual feeding stations, and the control means for said interceptors may be embodied in any suitable manner.
In a preferred embodiment of the invention, the interceptor associated with each feeding station is formed by a thin diaphragm which is inserted, in its active position, under the bottom outlets of the respective feeding station, between these outlets and the path of travel of the reciprocatory pusher which transfers the cigarette layer formed under the outlets of said feeding channels into the collecting container.
According to a further advantageous feature of the invention, said intercepting diaphragm is of flexible nature and is secured at one end to a winding roller on which it is wound when at rest, while it is unwound and horizontally slidably guided under the bottom outlets of the feeding channels when it is activated. This embodiment has the advantageous characteristics of a reduced size and an easy control of the winding roller, e.g. by means of an associated electric motor of the step-by-step type.